This invention relates to lubricating oil compositions. More particularly, this invention relates to lubricating oil compositions containing boron, relatively low levels of sulfur and as an optional ingredient relatively low levels of phosphorus.
Engine lubricating oils require the presence of additives to protect the engine from wear. For over 40 years, the principal antiwear additive for engine lubricating oils has been zinc dialkyl dithiophosphate (ZDDP). However, ZDDP is typically used in the lubricating oil at a sufficient concentration to provide a phosphorus content of 0.10% by weight or higher in order to pass required industry standard tests for antiwear. Since phosphorus may result in the deactivation of emission control catalysts used in automotive exhaust systems, a reduction in the amount of phosphorus-containing additives (e.g., ZDDP) in the oil would be desirable. Additionally, the allowable level of sulfur in diesel and gasoline fuels is expected to drop to 15 parts per million (ppm) with zero sulfur fuel already being introduced in select locations. Therefore, a substantial portion of the sulfur in the emissions can, in the near future, be attributed to the lubricant. The problem therefore is to provide for a reduction in the amount of phosphorus- and sulfur-containing additives in lubricating oil compositions and yet provide such lubricating oil compositions with required antiwear properties. The present invention provides a solution to this problem by providing lubricating oil compositions containing additives that function as complete or partial replacements for ZDDP.
This invention relates to a lubricating oil composition, comprising: (A) a base oil and (B) a boron-containing compound represented by the formulae 
wherein in Formulae (B-I), (B-II) and (B-III), each R is independently an organic group and any two adjacent R groups may together form a cyclic group; the lubricating oil composition containing sulfur, boron and optionally phosphorus with the ratio of sulfur to boron to phosphorus being represented by the formula
S1+5B1+3P1 greater than 0.35
wherein S1 is the concentration in percent bit weight of sulfur in the composition, B1 is the concentration in percent by weight of boron in the composition, and P1 is the concentration in percent by weight of phosphorus in the composition; the concentration of sulfur in the lubricating oil composition being from about 0.01% to about 0.25% by weight; the concentration of phosphorus in the lubricating oil composition being up to about 0.08% by weight. In one embodiment, the composition further comprises (C) an acylated nitrogen-containing compound having a substituent of at least about 10 aliphatic carbon atoms. In one embodiment, the composition further comprises (D) an alkali or alkaline earth metal salt of an organic sulfur acid, a carboxylic acid or a phenol. In one embodiment, the composition further comprises (E) an alkali or alkaline(earth metal salt of a hydrocarbon-substituted saligenin. In one embodiment, the composition further comprises (F) a metal salt of a phosphorus-containing compound. In one embodiment, the composition further comprises (G) a dispersant viscosity index modifier. In one embodiment, the composition further comprises (H) one or more additional optional additives. The inventive composition may be made by blending components (A) and (B), and optionally one or more of components (C) to (H), using known blending techniques and any order of mixing or addition.
The term xe2x80x9chydrocarbylxe2x80x9d denotes a group having a carbon atom directly attached to the remainder of the molecule and having a hydrocarbon or predominantly hydrocarbon character within the context of this invention. Such groups include the following:
(1) Purely hydrocarbon groups; That is, aliphatic, (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic- and alicyclic-substituted aromatic, aromatic-substituted aliphatic and alicyclic groups, and the like, as well as cyclic groups wherein the ring is completed through another portion of the molecule (that is, any two indicated substituents may together form an alicyclic group). Such groups are known to those skilled in the art. Examples include methyl, ethyl, octyl, decyl, octadecyl, cyclohexyl, phenyl, etc.
(2) Substituted hydrocarbon groups; that is, groups containing non-hydrocarbon substituents which do not alter the predominantly hydrocarbon character of the group. Those skilled in the art will be aware of suitable substituents. Examples include hydroxy, nitro, cyano, alkoxy, acyl, etc.
(3) Hetero groups; that is, groups which, while predominantly hydrocarbon in character, contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, nitrogen, oxygen and sulfur.
In general, no more than about three substituents or hetero atoms, and preferably no more than one, will be present for each 10 carbon atoms in the hydrocarbyl group.
Terms such as xe2x80x9calkyl-based,xe2x80x9d xe2x80x9caryl-based,xe2x80x9d and the like have meanings analogous to the above with respect to alkyl groups, aryl groups and the like.
The terms xe2x80x9chydrocarbonxe2x80x9d and xe2x80x9chydrocarbon-basedxe2x80x9d have the same meaning and can be used interchangeably with the term hydrocarbyl when referring to molecular groups having a carbon atom attached directly to the remainder of a molecule.
The term xe2x80x9clowerxe2x80x9d as used herein in conjunction with terms such as hydrocarbyl, alkyl, alkenyl, alkoxy, and the like, is intended to describe such groups which contain a total of up to 7 carbon atoms.
The term xe2x80x9coil-solublexe2x80x9d refers to a material that is soluble in mineral oil to the extent of at least about one gram per liter at 25xc2x0 C.
The term xe2x80x9cTBNxe2x80x9d refers to total base number. This is the amount of acid (perchloric or hydrochloric) needed to neutralize all or part of a material""s basicity, expressed as milligrams of KOH per gram of sample.
The Lubricating Oil Composition
The inventive lubricating oil composition is comprised of one or more base oils which are generally present in a major amount (i.e. an amount greater than about 50% by weight). Generally, the base oil is present in an amount greater than about 60%, or greater than about 70%, or greater than about 75% by weight of the lubricating oil composition.
The inventive lubricating oil composition may have a viscosity of up to about 16.3 cSt at 100xc2x0 C., and in one embodiment about 5 to about 16.3 cSt at 100xc2x0 C., and in one embodiment about 6 to about 13 cSt at 100xc2x0 C.
The inventive lubricating oil composition may have an SAE Viscosity Grade of 0W, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40 or 10W-50.
The inventive lubricating oil composition contains sulfur, boron and optionally phosphorus. The ratio of sulfur to boron to phosphorus may be represented by the formula
S1+5B1+3P1 greater than T
wherein S1 is the concentration in percent bad weight of sulfur in the composition, B1 is the concentration in percent by weight of boron in the composition, P1 is the concentration in percent by weight of phosphorus in the composition, and T is the sum of S1+5B1+3P1. In one embodiment, T is greater than 0.35, and in one embodiment greater than 0.36, and in one embodiment greater than 0.38, and in one embodiment it is greater than 0.40, and in one embodiment greater than 0.42, and in one embodiment it is greater than 0.45, and in one embodiment it is greater than 0.50.
The inventive lubricating oil composition may have a sulfur content of about 0.01 to about 0.25% by weight, and in one embodiment about 0.02 to about 0.25% by weight, and in one embodiment about 0.03 to about 0.25% by weight, and in one embodiment about 0.04 to about 0.25% by weight, and in one embodiment about 0.05 to about 0.25%, and in one embodiment about 0.07 to about 0.25% by weight, and in one embodiment about 0.10 to about 0.25% by weight, and in one embodiment about 0.01 to about 0.20% by weight, and in one embodiment about 0.02 to about 0.20% by weight, and in one embodiment about 0.03 to about 0.20% by weight, and in one embodiment about 0.04 to about 0.20% by weight, and in one embodiment about 0.05 to about 0.20% by weight, and in one embodiment about 0.07 to about 0.20% by weight, and in one embodiment about 0.10 to about 0.20% by weight, and in one embodiment about 0.15 to about 0.20% by weight, and in one embodiment about 0.17% by weight, and in one embodiment about 0.01 to about 0.15% by weight, and in one embodiment about 0.02 to about 0.15% by weight, and in one embodiment about 0.03 to about 0.15% by weight, and in one embodiment about 0.04 to about 0.15% by weight, and in one embodiment about 0.05 to about 0.15% by weight, and in one embodiment about 0.07 to about 0.15% by weight, and in one embodiment about 0.10 to about 0.15% by weight.
The inventive lubricating oil composition may have a boron content in the range of about 0.01 to about 0.2% by weight, and in one embodiment about 0.015 to about 0.12% by weight, and in one embodiment about 0.05 to about 0.1% by weight.
The inventive lubricating oil composition may have a phosphorus content of up to about 0.08% by weight, and in one embodiment up to about 0.075% by weight, and in one embodiment up to about 0.07% by weight, and in one embodiment up to about 0.06% by weight, and in one embodiment up to about 0.05% by weight, and in one embodiment up to about 0.04% by weight, and in one embodiment up to about 0.035% by weight, and in one embodiment up to about 0.03% by weight, and in one embodiment up to about 0.025% by weight, and in one embodiment up to about 0.02% by weight, and in one embodiment up to about 0.015% by weight, and in one embodiment up to about 0.01% by weight. In one embodiment, the phosphorus content is in the range of about 0.01 to about 0.08% by weight, and in one embodiment about 0.02 to about 0.07% by weight, and in one embodiment about 0.02 to about 0.06% by weight, and in one embodiment about 0.03 to about 0.06% by weight.
The ash content of the inventive lubricating oil composition as determined by the procedures in ASTM D-874-96 may be in the range of about 0.3 to about 1.4% by weight, and in one embodiment about 0.3 to about 1.2% by weight, and in one embodiment about 0.3 to about 1.1% by weight, and in one embodiment about 0.5 to about 1.1% by weight, and in one embodiment about 0.7 to about 1.1% by weight, and in one embodiment about 0.8 to about 1.0% by weight.
In one embodiment, the inventive lubricating oil composition is characterized by a chlorine content of up to about 100 ppm, and in one embodiment up to about 50 ppm, and in one embodiment up to about 30 ppm, and in one embodiment up to about 10 ppm.
The inventive lubricating oil compositions are characterized by reduced phosphorus and sulfur levels when compared to those in the prior art, and yet, at least in one embodiment, exhibit antiwear properties that are sufficient to pass industry standard tests for antiwear. In one embodiment, the inventive lubricating oil composition exhibits enhanced thermal stability, seal compatability and/or lead corrosion resistance characteristics. The inventive lubricating oil compositions are useful as engine lubricating oil compositions.
(A) The Base Oil
The base oil used in the inventive lubricating oil composition may be selected from any of the base oils in Groups I-V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The five base oil groups are as follows:
The base oil used in the inventive lubricating oil composition may be a natural oil, synthetic oil or mixture thereof. The natural oils that are useful include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale are also useful. Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinoylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyl, alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like.
Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils that can be used. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1500, etc.) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-8 fatty acid esters, or the C13Oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils that can be used comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.) Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.
Esters useful as synthetic oils also include those made from C5 to C12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.
The base oil may be a poly-alpha-olefin (PAO). Typically, the poly-alpha-olefins are derived from monomers having from about 4 to about 30, or from about 4 to about 20, or from about 6 to about 16 carbon atoms. Examples of useful PAOs include those derived from octene, decene, mixtures thereof, and the like. These PAOs may have a viscosity from about 2 to about 15, or from about 3 to about 12, or from about 4 to about 8 cSt at 100xc2x0 C. Examples of useful PAOs include 4 cSt at 100xc2x0 C. poly-alpha-olefins, 6 cSt at 100xc2x0 C. poly-alpha-olefins, and mixtures thereof. Mixtures of mineral oil with the foregoing poly-alpha-olefins may be used.
The base oil may be an oil derived from Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons are made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. These hydrocarbons typically require further processing in order to be useful as the base oil. For example, the hydrocarbons may be hydroisomerized using the process disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using the process disclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940; dewaxed using the process disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed using the process disclosed in U.S. Pat. Nos. 6,013,171, 6,080,301 or 6,165,949. These patents are incorporated herein by reference for their disclosures of processes for treating Fischer-Tropsch synthesized hydrocarbons and the resulting products made from such processes.
Unrefined, refined and rerefined oils, either natural or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.
(B) Boron-Containing Compound
The boron-containing compound is a compound represented by one or more of the formulae 
wherein in Formulae (B-I), (B-II) and (B-III), each R is independently an organic group and any two adjacent R groups may together form a cyclic group. Mixtures of two or more of the foregoing may be used. In one embodiment, R is a hydrocarbyl group. The total number of carbon atoms in the R groups in each formula must be sufficient to render the compound soluble in the base oil (A). Generally, the total number of carbon atoms in the R groups is at least about 8, and in one embodiment at least about 10, and in one embodiment at least about 12. There is no limit to the total number of carbon atoms in the R groups that is required, but a practical upper limit is about 400 or about 500 carbon atoms. In one embodiment, each R group is independently a hydrocarbyl group of 1 to about 100 carbon atoms, and in one embodiment 1 to about 50 carbon atoms, and in one embodiment 1 to about 30 carbon atoms, and in one embodiment 1 to about 10 carbon atoms, with the proviso that the total number of carbons in the R group is at least about 8. Each R group may be the same as the other, although they may be different. Examples of useful R groups include isopropyl, n-butyl, isobutyl, amyl, 4-methyl-2-pentyl, 2-ethyl-1-hexyl, isooctyl, decyl, dodecyl, tetradecyl, 2-pentenyl, dodecenyl, phenyl, naphthyl, alkylphenyl, alkylnaphthyl, phenylalkyl, naphthylalkyl, alkylphenylalkyl, alkylnaphthylalkyl, and the like.
In one embodiment, the boron-containing compound (B) is a compound represented by the formula B(OC5H11)3 or B(OC4H9)3. A useful boron-containing compound is available from Mobil under the trade designation MCP-1286; this material is identified as a borated ester.
In one embodiment, the boron-containing compound (B) is a compound represented by the formula 
wherein in Formula (B-I-1): R1, R2, R3 and R4 are independently hydrocarbyl groups of 1 to about 12 carbon atoms; and R5 and R6 are independently alkylene groups of 1 to about 6 carbon atoms, and in one embodiment about 2 to about 4 carbon atoms, and in one embodiment about 2 or about 3 carbon atoms. In one embodiment, R1 and R2 independently contain 1 to about 6 carbon atoms, and in one embodiment each is a t-butyl group. In one embodiment, R3 and R4 are independently hydrocarbyl groups of about 2 to about 12 carbon atoms, and in one embodiment about 8 to about 10 carbon atoms. In one embodiment, R5 and R6 are independently xe2x80x94CH2CH2xe2x80x94 or xe2x80x94CH2CH2CH2xe2x80x94.
In one embodiment the boron-containing compound (B) is a compound represented by the formula: 
wherein in Formula (B-II-1): R1, R2, R3, R4, R5, R6, R7 and R8 are independently hydrogen or hydrocarbyl groups. Each of the hydrocarbyl groups may contain from 1 to about 12 carbon atoms, and in one embodiment 1 to about 4 carbon atoms. An example is 2,2xe2x80x2-oxy-bis-(4,4,6-timethyl-1,3,2-dioxaborinane).
A useful boron-containing compound (B) is available from Crompton Corporation under the trade designation LA-2607. This material is identified as a phenolic borate having the structure represented by Formula (B-I-1) wherein R1 and R2 are each t-butyl, R3 and R4 are hydrocarbyl groups of 2 to about 12 carbon atoms, R5 is xe2x80x94CH2CH2xe2x80x94, and R6 is xe2x80x94CH2CH2CH2xe2x80x94.
The boron-containing compound (B) may be employed in the inventive lubricating oil composition at a sufficient concentration to provide the lubricating oil composition with a boron concentration in the range of about 0.01 to about 0.2% by weight, and in one embodiment about 0.015 to about 0.12% by weight, and in one embodiment about 0.05 to about 0.1% by weight. These compounds can be added directly to the lubricating oil composition. In one embodiment, however, they are diluted with a substantially inert, normally liquid organic diluent such as mineral oil, synthetic oil (e.g., ester of dicarboxylic acid), naptha, alkylated (e.g. C10-C13 alkyl) benzene, toluene or xylene to form an additive concentrate. These concentrates usually contain from about 1% to about 99% by weight, and in one embodiment about 10% to about 90% by weight of the diluent.
(C) Acylated Nitrogen-Containing Compound
In one embodiment, the inventive lubricating oil composition further comprises an acylated nitrogen-containing compound having a substituent of at least about 10 aliphatic carbon atoms. These compounds typically function as ashless dispersants in lubricating oil compositions.
A number of acylated, nitrogen-containing compounds having a substituent of at least about 10 aliphatic carbon atoms and made by reacting a carboxylic acid acylating agent with an amino compound are known to those skilled in the art. In such compositions the acylating agent is linked to the amino compound through an imido, amido, amidine or salt linkage. The substituent of at least about 10 aliphatic carbon atoms may be in either the carboxylic acid acylating agent derived portion of the molecule or in the amino compound derived portion of the molecule. In one embodiment, it is in the acylating agent portion. The acylating agent can vary from formic acid and its acyl derivatives to acylating agents having high molecular weight aliphatic substituents of up to about 5,000, 10,000 or 20,000 carbon atoms. The amino compounds are characterized by the presence within their structure of at least one HN less than group.
In one embodiment, the acylating agent is a mono- or polycarboxylic acid (or reactive equivalent thereof) such as a substituted succinic or propionic acid and the amino compound is a polyamine or mixture of polyamines, most typically, a mixture of ethylene polyamines. The amine also may be a hydroxyalkyl-substituted polyamine. The aliphatic substituent in such acylating agents is a hydrocarbon-based group that typically averages at least about 30 or at least about 50 and up to about 400 carbon atoms.
Illustrative hydrocarbon based groups containing at least 10 carbon atoms are n-decyl, n-dodecyl, tetrapropylene, n-octadecyl, oleyl, chlorooctadecyl, triicontanyl, etc. Generally, the hydrocarbon-based substituents are made from homo- or interpolymers (e.g., copolymers, terpolymers) of mono- and di-olefins having 2 to 10 carbon atoms, such as ethylene, propylene, 1-butene, isobutene, butadiene, isoprene, 1-hexene, 1-octene, etc. Typically, these olefins are 1-monoolefins. The substituent can also be derived from the halogenated (e.g., chlorinated or brominated) analogs of such homo- or interpolymers. The substituent can, however, be made from other sources, such as monomeric high molecular weight alkenes (e.g., 1-tetracontene) and chlorinated analogs and hydrochlorinated analogs thereof, aliphatic petroleum fractions, particularly paraffin waxes and cracked and chlorinated analogs and hydrochlorinated analogs thereof, white oils, synthetic alkenes such as those produced by the Ziegler-Natta process (e.g., poly(ethylene) greases) and other sources known to those skilled in the art. Any unsaturation in the substituent may be reduced or eliminated by hydrogenation according to procedures known in the art.
The hydrocarbon-based substituents are substantially saturated, that is, they contain no more than one carbon-to-carbon unsaturated bond for every ten carbon-to-carbon single bonds present. Usually, they contain no more than one carbon-to-carbon non-aromatic unsaturated bond for every 50 carbon-to-carbon bonds present.
The hydrocarbon-based substituents are also substantially aliphatic in nature, that is, they contain no more than one non-aliphatic moiety (cycloalkyl, cycloalkenyl or aromatic) group of 6 or less carbon atoms for every 10 carbon atoms in the substituent. Usually, however, the substituents contain no more than one such non-aliphatic group for every 50 carbon atoms, and in many cases, they contain no such non-aliphatic groups at all; that is, the typical substituents are purely aliphatic. Typically, these purely aliphatic substituents are alkyl or alkenyl groups.
Specific examples of the substantially saturated hydrocarbon-based substituents containing an average of more than about 30 carbon atoms are the following:
a mixture of poly(ethylene/propylene) groups of about 35 to about 70 carbon atoms;
a mixture of the oxidatively or mechanically degraded poly(ethylene/propylene) groups of about 35 to about 70 carbon atoms;
a mixture of poly(propylene/1-hexene) groups of about 80 to about 150 carbon atoms;
a mixture of poly(isobutene) groups having an average of about 50 to about 200 carbon atoms.
A useful source of the hydrocarbon-based substituents are poly(isobutene)s obtained by polymerization of a C4 refinery stream having a butene content of about 35 to about 75 weight percent and isobutene content of about 30 to about 60 weight percent in the presence of a Lewis acid catalyst such as aluminum trichloride or boron trifluoride. These polybutenes contain predominantly (greater than 80% of total repeating units) isobutene repeating units of the configuration 
In one embodiment, the substituent is a polyisobutene group derived from a polyisobutene having a high methylvinylidene isomer content, that is, at least about 70% methylvinylidene, and in one embodiment at least about 80% methylvinylidene. Suitable high methylvinylidene polyisobutenes include those prepared using boron trifluoride catalysts. The preparation of such polyisobutenes in which the methylvinylidene isomer comprises a high percentage of the total olefin composition is described in U.S. Pat. Nos. 4,152,499 and 4,605,808, the disclosures of each of which are incorporated herein by reference.
In one embodiment, the carboxylic acid acylating agent is a hydrocarbon substituted succinic acid or anhydride. The substituted succinic acid or anhydride consists of hydrocarbon-based substituent groups and succinic groups wherein the substituent groups are derived from a polyalkene, said acid or anhydride being characterized by the presence within its structure of an average of at least about 0.9 succinic group for each equivalent weight of substituent groups, and in one embodiment about 0.9 to about 2.5 succinic groups for each equivalent weight of substituent groups. The polyalkene generally has number average molecular weight ({overscore (M)}n) of at least about 700, and in one embodiment about 700 to about 2000, and in one embodiment about 900 to about 1800. The ratio between the weight average molecular weight ({overscore (M)}w) and the ({overscore (M)}n) (that is, the {overscore (M)}w/{overscore (M)}n) can range from about 1 to about 10, or about 1.5 to about 5. In one embodiment the polyalkene has an {overscore (M)}w/{overscore (M)}n value of about 2.5 to about 5. For purposes of this invention, the number of equivalent weights of substituent groups is deemed to be the number corresponding to the quotient obtained by dividing the {overscore (M)}n value of the polyalkene from which the substituent is derived into the total weight of the substituent groups present in the substituted succinic acid. Thus, if a substituted succinic acid is characterized by a total weight of substituent group of 40,000 and the {overscore (M)}n value for the polyalkene from which the substituent groups are derived is 2000, then that substituted succinic acylating agent is characterized by a total of 20 (40,000/2000=20) equivalent weights of substituent groups.
In one embodiment the carboxylic acid acylating agent is a substituted succinic acid or anhydride, said substituted succinic acid or anhydride consisting of hydrocarbon-based substituent groups and succinic groups wherein the substituent groups are derived from polybutene in which at least about 50% of the total units derived from butenes is derived from isobutylene. The polybutene is characterized by an {overscore (M)}n value of about 1500 to about 2000 and an {overscore (M)}w/{overscore (M)}n value of about 3 to about 4. These acids or anhydrides are characterized by the presence within their structure of an average of about 1.5 to about 2.5 succinic groups for each equivalent weight of substituent groups.
In one embodiment the carboxylic acid is at least one substituted succinic acid or anhydride, said substituted succinic acid or anhydride consisting of substituent groups and succinic groups wherein the substituent groups are derived from polybutene in which at least about 50% of the total units derived from butenes is derived from isobutylene. The polybutene has an {overscore (M)}n value of about 800 to about 1200 and an {overscore (M)}w/{overscore (M)}n value of about 2 to about 3. The acids or anhydrides are characterized by the presence within their structure of an average of about 0.9 to about 1.2 succinic groups for each equivalent weight of substituent groups.
The amino compound is characterized by the presence within its structure of at least one HN less than group and can be a monoamine or polyamine. Mixtures of two or more amino compounds can be used in the reaction with one or more acylating reagents. In one embodiment, the amino compound contains at least one primary amino group (i.e., xe2x80x94NH2) and more preferably the amine is a polyamine, especially a polyamine containing at least two xe2x80x94NHxe2x80x94 groups, either or both of which are primary or secondary amines. The amines may be aliphatic, cycloaliphatic, aromatic or heterocyclic amines.
Among the useful amines are the alkylene polyamines, including the polyalkylene polyamines. The alkylene polyamines include those conforming to the formula 
wherein n is from 1 to about 14; each R is independently a hydrogen atom, a hydrocarbyl group or a hydroxy-substituted or amine-substituted hydrocarbyl group having up to about 30 atoms, or two R groups on different nitrogen atoms can be joined together to form a U group, with the proviso that at least one R group is a hydrogen atom and U is an alkylene group of about 2 to about 10 carbon atoms. U may be ethylene or propylene. Alkylene polyamines where each R is hydrogen or an amino-substituted hydrocarbyl group with the ethylene polyamines and mixtures of ethylene polyamines are useful. Usually n will have an average value of from about 2 to about 10. Such alkylene polyamines include methylene polyamine, ethylene polyamines, propylene polyamines, butylene polyamines, pentylene polyamines, hexylene polyamines, heptylene polyamines, etc. The higher homologs of such amines and related amino alkyl-substituted piperazines are also included.
Alkylene polyamines that are useful include ethylene diamine, triethylene tetramine, propylene diamine, trimethylene diamine, hexamethylene diamine, decamethylene diamine, octamethylene diamine, di(heptamethylene)triamine, tripropylene tetramine, tetraethylene pentamine, trimethylene diamine, pentaethylene hexamine, di(trimethylene)triamine, N-(2-aminoethyl)piperazine, 1,4-bis(2-aminoethyl)piperazine, and the like. Higher homologs as are obtained by condensing two or more of the above-illustrated alkylene amines are useful, as are mixtures of two or more of any of the afore-described polyamines.
Ethylene polyamines, such as those mentioned above, are especially useful for reasons of cost and effectiveness. Such polyamines are described in detail under the heading xe2x80x9cDiamines and Higher Aminesxe2x80x9d in The Encyclopedia of Chemical Technology, Second Edition, Kirk and Othmer, Volume 7, pages 27-39, Interscience Publishers, Division of John Wiley and Sons, 1965, which is hereby incorporated by reference for the disclosure of useful polyamines. Such compounds are prepared most conveniently by the reaction of an alkylene chloride with ammonia or by reaction of an ethylene imine with a ring-opening reagent such as ammonia, etc. These reactions result in the production of the somewhat complex mixtures of alkylene polyamines, including cyclic condensation products such as piperazines.
Other useful types of polyamine mixtures are those resulting from stripping of the above-described polyamine mixtures. In this instance, lower molecular weight polyamines and volatile contaminants are removed from an alkylene polyamine mixture to leave as residue what is often termed xe2x80x9cpolyamine bottomsxe2x80x9d. In general, alkylene polyamine bottoms can be characterized as having less than 2% by weight, usually less than 1% by weight material boiling below about 200xc2x0 C. In the instance of ethylene polyamine bottoms, which are readily available and found to be quite useful, the bottoms contain less than about 2% by weight total diethylene triamine (DETA) or triethylene tetramine (TETA). A typical sample of such ethylene polyamine bottoms obtained from the Dow Chemical Company of Freeport, Tex. designated xe2x80x9cE-100xe2x80x9d showed a specific gravity at 15.6xc2x0 C. of 1.0168, a percent nitrogen by weight of 33.15 and a viscosity at 40xc2x0 C. of 121 centistokes. Gas chromatography analysis of such a sample indicates it contains about 0.93% xe2x80x9cLight Endsxe2x80x9d (most probably DETA), 0.72% TETA, 21.74% tetraethylene pentamine and 76.61% pentaethylene hexamine and higher(by weight). These alkylene polyamine bottoms include cyclic condensation products such as piperazine and higher analogs of diethylenetriamine, triethylenetetramine and the like.
These alkylene polyamine bottoms can be reacted solely with the acylating agent, in which case the amino reactant consists essentially of alkylene polyamine bottoms, or they can be used with other amines and polyamines, or alcohols or mixtures thereof. In these latter cases at least one amino reactant comprises alkylene polyamine bottoms.
Other polyamines are described in, for example, U.S. Pat. Nos. 3,219,666 and 4,234,435, and these patents are hereby incorporated by reference for their disclosures of amines which can be reacted with the acylating agents described above to form useful acylated nitrogen-containing compounds.
In one embodiment, the amine may be a hydroxyamine. Typically, the hydroxyamines are primary or secondary alkanol amines or mixtures thereof. Such amines can be represented by the formulae:
H2Nxe2x80x94Rxe2x80x2xe2x80x94OH
or
RN(H)xe2x80x94Rxe2x80x2xe2x80x94OH
wherein R is a hydrocarbyl group of one to about eight carbon atoms or hydroxyhydrocarbyl group of two to about eight carbon atoms, and in one embodiment one to about four, and Rxe2x80x2 is a divalent hydrocarbyl group of about two to about 18 carbon atoms, and in one embodiment two to about four. The group xe2x80x94Rxe2x80x2xe2x80x94OH in such formulae represents the hydroxyhydrocarbyl group. Rxe2x80x2 can be an acyclic, alicyclic or aromatic group. Typically, Rxe2x80x2 is an acyclic straight or branched alkylene group such as an ethylene, 1,2-propylene, 1,2-butylene, 1,2-octadecylene, etc. group. Typically, R is a methyl, ethyl, propyl, butyl, pentyl or hexyl group.
Examples of these alkanolamines include mono- and di-ethanol amine, ethylethanolamine, etc.
The hydroxyamines can also be an ether N-(hydroxyhydrocarbyl)-amine. These are hydroxypoly(hydrocarbyloxy) analogs of the above-described hydroxy amines (these analogs also include hydroxyl-substituted oxyalkylene analogs). Such N-(hydroxyhydrocarbyl)amines can be conveniently prepared by reaction of epoxides with afore-described amines and can be represented by the formulae:
H2Nxe2x80x94(Rxe2x80x2O)xxe2x80x94H
or
RN(H)xe2x80x94(Rxe2x80x2O)xH
wherein x is a number from about 2 to about 15 and R and Rxe2x80x2 are as described above. R may also be a hydroxypoly(hydrocarbyloxy) group.
The acylated nitrogen-containing compounds include amine salts, amides, imides, amidines, amidic acids, amidic salts and imidazolines as well as mixtures thereof. To prepare the acylated nitrogen-containing compounds from the acylating reagents and the amino compounds, one or more acylating reagents and one or more amino compounds are heated, optionally in the presence of a normally liquid, substantially inert organic liquid solvent/diluent, at temperatures in the range of about 80xc2x0 C. up to the decomposition point of either the reactants or the carboxylic derivative but normally at temperatures in the range of about 100xc2x0 C. up to about 300xc2x0 C. provided 300xc2x0 C. does not exceed the decomposition point. Temperatures of about 125xc2x0 C. to about 250xc2x0 C. are normally used. The acylating reagent and the amino compound are reacted in amounts sufficient to provide from about one-half equivalent up to about 2 moles of amino compound per equivalent of acylating reagent.
Many patents have described useful acylated nitrogen-containing compounds including U.S. Pat. Nos. 3,172,892; 3,219,666; 3,272,746; 3,310,492; 3,341,542; 3,444,170; 3,455,831; 3,455,832; 3,576,743; 3,630,904; 3,632,511; 3,804,763; and 4,234,435. A typical acylated nitrogen-containing compound of this class is that made by reacting a poly(isobutene)-substituted succinic acid acylating agent (e.g., anhydride, acid, ester, etc.) wherein the poly(isobutene) substituent has between about 50 to about 400 carbon atoms with a mixture of ethylenepolyamines having about 3 to about 7 amino nitrogen atoms per ethylenepolyamine and about 1 to about 6 ethylene units. The above-noted U.S. patents are hereby incorporated by reference for their disclosure of acylated amino compounds and their method of preparation.
Another type of acylated nitrogen-containing compound belonging to this class is that made by reacting a carboxylic acid acylating agent with a polyamine, wherein the polyamine is the product made by condensing a hydroxy material with an amine. These compounds are described in U.S. Pat. No. 5,053,152 which is incorporated herein by reference for its disclosure of such compounds.
Another type of acylated nitrogen-containing compound belonging to this class is that made by reacting the afore-described alkyleneamines with the afore-described substituted succinic acids or anhydrides and aliphatic monocarboxylic acids having from 2 to about 22 carbon atoms. In these types of acylated nitrogen compounds, the mole ratio of succinic acid to monocarboxylic acid ranges from about 1:0.1 to about 1:1. Typical of the monocarboxylic acid are formic acid, acetic acid, dodecanoic acid, butanoic acid, oleic acid, stearic acid, the commercial mixture of stearic acid isomers known as isostearic acid, tall oil acid, etc. Such materials are more fully described in U.S. Pat. Nos. 3,216,936 and 3,250,715 which are hereby incorporated by reference for their disclosures in this regard.
Still another type of acylated nitrogen-containing compound that may be useful is the product of the reaction of a fatty monocarboxylic acid of about 12-30 carbon atoms and the afore-described alkyleneamines, typically, ethylene-, propylene- or trimethylenepolyamines containing 2 to 8 amino groups and mixtures thereof. The fatty monocarboxylic acids are generally mixtures of straight and branched chain fatty carboxylic acids containing 12-30 carbon atoms. A widely used type of acylated nitrogen compound is made by reacting the afore-described alkylenepolyamines with a mixture of fatty acids having from 5 to about 30 mole percent straight chain acid and about 70 to about 95% mole branched chain fatty acids. Among the commercially available mixtures are those known widely in the trade as isostearic acid. These mixtures are produced as a by-product from the dimerization of unsaturated fatty acids as described in U.S. Pat. Nos. 2,812,342 and 3,260,671.
The branched chain fatty acids can also include those in which the branch is not alkyl in nature, such as found in phenyl and cyclohexyl stearic acid and the chloro-stearic acids. Branched chain fatty carboxylic acid/alkylene polyamine products have been described extensively in the art. See for example, U.S. Pat. Nos. 3,110,673; 3,251,853; 3,326,801; 3,337,459; 3,405,064; 3,429,674; 3,468,639; 3,857,791. These patents are hereby incorporated by reference for their disclosure of fatty acid/polyamine condensates for use in lubricating oil formulations.
In one embodiment, the lubricating oil composition is characterized by a chlorine level of up to about 100 ppm, and in one embodiment up to about 50 ppm, and in one embodiment up to about 30 ppm, and in one embodiment up to about 10 ppm. This necessitates that the acylated nitrogen-containing compound be derived from a reaction product that is chlorine-free or contain such low chlorine levels that the addition of such compound to the lubricating oil composition results in the formation of a lubricating oil composition with the above-indicated chlorine level. In one embodiment, the acylated nitrogen-containing compound is contained in or derived from a reaction product that has a chlorine content of up to about 50 ppm, and in one embodiment up to about 25 ppm, and in one embodiment up to about 10 ppm. In one embodiment, the acylated nitrogen-containing compound is contained in or derived from a reaction product that is chlorine free.
The acylated nitrogen-containing compound (C) may be employed in the inventive lubricating oil composition at a concentration in the range of up to about 10% by weight, and in one embodiment about 1 to about 10% percent by weight, and in one embodiment about 2 to about 5% by weight, and in one embodiment about 2 to about 3% by weight. These compounds can be added directly to the lubricating oil composition. In one embodiment, however, they are diluted with a substantially inert, normally liquid organic diluent such as mineral oil, synthetic oil (e.g., ester of dicarboxylic acid), naphtha, alkylated (e.g., C10-C13 alkyl)benzene, toluene or xylene to form an additive concentrate. These concentrates usually contain from about 1% to about 99% by weight, and in one embodiment about 10% to about 90% by weight of the diluent.
(D) Alkali or Alkaline Earth Metal Salt of Organic Sulfur Acid, Carboxylic Acid, Lactone or Phenol
The alkali metal or alkaline earth metal salts (D) are salts of organic sulfur acids, carboxylic acids, lactones or phenols. These salts may be neutral or overbased. The former contain an amount of metal cation just sufficient to neutralize the acidic groups present in the salt anion; the latter contain an excess of metal cation and are often termed basic, hyperbased or superbased salts
The terminology xe2x80x9cmetal ratioxe2x80x9d is used herein to designate the ratio of the total chemical equivalents of the metal in the overbased salt to the chemical equivalents of the metal in the salt which would be expected to result in the reaction between the organic acid to be overbased and the basically reacting metal compound according to the known chemical reactivity and stoichiometry of the two reactants. Thus, in a normal or neutral salt the metal ratio is one and, in an overbased salt, the metal ratio is greater than one. The overbased salts used as component (D) in this invention may have metal ratios of at least about 1.2:1, and in one embodiment at least about 1.4:1. Often they have ratios of at least about 2:1, and in one embodiment at least about 4:1. These salts may have metal ratios not exceeding about 20:1. Salts having ratios of about 1.5:1 to about 15:1 may be used.
The organic sulfur acids are oil-soluble organic sulfur acids such as sulfonic, sulfamic, thiosulfonic, sulfinic, sulfenic, partial ester sulfuric, sulfurous and thiosulfuric acid. Generally they are salts of aliphatic or aromatic sulfonic acids.
The sulfonic acids include the mono- or poly-nuclear aromatic or cycloaliphatic compounds. The sulfonic acids may be represented for the most part by one of the following formulae:
xe2x80x83R1(SO3H)rxe2x80x83xe2x80x83(D-I)
(R2)xT(SO3H)yxe2x80x83xe2x80x83(D-II)
wherein in Formulae (D-I) and (D-II), T is an aromatic nucleus such as, for example, benzene, naphthalene, anthracene, phenanthrene, diphenylene oxide, thianthrene, phenothioxine, diphenylene sulfide, phenothiazine, diphenyl oxide, diphenyl sulfide, diphenylamine, etc; R1 and R2 are each independently aliphatic groups, R1 contains at least about 15 carbon atoms, the sum of the carbon atoms in R2 and T is at least about 15, and r, x and y are each independently 1 or greater. Specific examples of R1 are groups derived from petrolatum, saturated and unsaturated paraffin wax, and polyolefins, including polymerized C2, C3, C4, C5, C6, etc., olefins containing from about 15 to about 7000 or more carbon atoms. The groups T, R1, and R2 in the above formulae can also contain other inorganic or organic substituents in addition to those enumerated above such as, for example, hydroxy, mercapto, halogen, nitro, amino, nitroso, sulfide, disulfide, etc. The subscript x is generally 1-3, and the subscripts r and y generally have an average value of about 1-4 per molecule.
The following are specific examples of oil-soluble sulfonic acids coming within the scope of Formulae (D-I) and (D-II), and it is to be understood that such examples serve also to illustrate the salts of such sulfonic acids useful in this invention. In other words, for every sulfonic acid enumerated it is intended that the corresponding neutral and basic metal salts thereof are also understood to be illustrated. Such sulfonic acids include mahogany sulfonic acids; bright stock sulfonic acids; sulfonic acids derived from lubricating oil fractions having a Saybolt viscosity from about 100 seconds at 100xc2x0 F. to about 200 seconds at 210xc2x0 F.; petrolatum sulfonic acids; mono- and poly-wax substituted sulfonic and polysulfonic acids of, e.g., benzene, naphthalene, phenol, diphenyl ether, naphthalene disulfide, diphenylamine, thiophene, alpha-chloronaphthalene, etc.; other substituted sulfonic acids such as alkylbenzene sulfonic acids (where the alkyl group has at least 8 carbons), cetylphenol mono-sulfide sulfonic acids, dicetyl thianthrenedisulfonic acids, dilaurylbetanaphthylsulfonic acids, and alkaryl sulfonic acids such as dodecylbenzene xe2x80x9cbottomsxe2x80x9d sulfonic acids.
The latter are acids derived from benzene which has been alkylated with propylene tetramers or isobutene trimers to introduce 1, 2, 3, or more branched-chain C12 substituents on the benzene ring. Dodecylbenzene bottoms, principally mixtures of mono- and di-dodecylbenzenes, are available as by-products from the manufacture of household detergents. Similar products obtained from alkylation bottoms formed during manufacture of linear alkylsulfonates (LAS) are also useful in making the sulfonates used in this invention.
The production of sulfonates from detergent manufacture byproducts is well known to those skilled in the art. See, for example, the article xe2x80x9cSulfonatesxe2x80x9d in Kirk-Othmer xe2x80x9cEncyclopedia of Chemical Technologyxe2x80x9d, Second Edition, Vol. 19, pp. 291 et seq. published by John Wiley and Sons, N.Y. (1969).
Other descriptions of neutral and basic sulfonate salts and techniques for making them can be found in the following U.S. Pat. Nos.: 2,174,110; 2,174,506; 2,174,508; 2,193,824; 2,197,800; 2,202,781; 2,212,786; 2,213,360; 2,228,598; 2,223,676; 2,239,974; 2,263,312; 2,276,090; 2,276,097; 2,315,514; 2,319,121; 2,321,022; 2,333,568; 2,333,788; 2,335,259; 2,337,552; 2,347,568; 2,366,027; 2,374,193; 2,383,319; 3,312,618; 3,471,403; 3,488,284; 3,595,790; and 3,798,012. These are hereby incorporated by reference for their disclosures in this regard. Also included are aliphatic sulfonic acids such as paraffin wax sulfonic acids, unsaturated paraffin wax sulfonic acids, hydroxy-substituted paraffin wax sulfonic acids, hexapropylenesulfonic acids, tetra-amylene sulfonic acids, polyisobutenesulfonic acids wherein the polyisobutene contains from 20 to 7000 or more carbon atoms, chloro-substituted paraffin wax sulfonic acids, nitro-paraffin wax sulfonic acids, etc; cycloaliphatic sulfonic acids such as petroleum naphthenesulfonic acids, cetylcyclopentyl sulfonic acids, laurylcyclohexylsulfonic acids, bis(di-isobutyl)cyclohexyl sulfonic acids, mono- or poly-wax substituted cyclohexylsulfonic acids, etc.
With respect to the sulfonic acids or salts thereof described herein and in the appended claims, it is intended herein to employ the term xe2x80x9cpetroleum sulfonic acidsxe2x80x9d or xe2x80x9cpetroleum sulfonatesxe2x80x9d to cover all sulfonic acids or the salts thereof derived from petroleum products. A particularly valuable group of petroleum sulfonic acids are the mahogany sulfonic acids (so called because of their reddish-brown color) obtained as a by-product from the manufacture of petroleum white oils by a sulfuric acid process.
The carboxylic acids from which suitable neutral and basic alkali metal and alkaline earth metal salts (D) may be made include aliphatic, cycloaliphatic, and aromatic mono- and polybasic carboxylic acids such as the naphthenic acids, alkyl- or alkenyl-substituted cyclopentanoic acids, alkyl- or alkenyl-substituted cyclohexanoic acids, alkyl- or alkenyl-substituted aromatic carboxylic acids. The aliphatic acids generally contain at least about 8 carbon atoms, and in one embodiment at least about 12 carbon atoms. Usually they have no more than about 400 carbon atoms. Generally, if the aliphatic carbon chain is branched, the acids are more oil-soluble for any given carbon atoms content. The cycloaliphatic and aliphatic carboxylic acids can be saturated or unsaturated. Specific examples include 2-ethylhexanoic acid, alpha-linolenic acid, propylenetetramer-substituted maleic acid, behenic acid, isostearic acid, pelargonic acid, capric acid, palmitoleic acid, linoleic acid, lauric acid, oleic acid, ricinoleic acid, decanoic acid, undecanoic acid, dioctylcyclopentane carboxylic acid, myristic acid, dilauryldecahydro-naphthalene carboxylic acid, stearyl-octahydroindene carboxylic acid, palmitic acid, and commercially available mixtures of two or more carboxylic acids such as tall oil acids, rosin acids, and the like.
A useful group of oil-soluble carboxylic acids useful in preparing the salts used in the present invention are the oil-soluble aromatic carboxylic acids. These acids are represented by the formula:
(R*)axe2x80x94Ar*(CXXH)mxe2x80x83xe2x80x83(D-III)
wherein in Formula (D-III), R* is an aliphatic hydrocarbon-based group of at least 4 carbon atoms, and no more than about 400 aliphatic carbon atoms, a is an integer of from one to four, Ar* is a polyvalent aromatic hydrocarbon nucleus of up to about 14 carbon atoms, each X is independently a sulfur or oxygen atom, and m is an integer of from one to four with the proviso that R* and a are such that there is an average of at least 8 aliphatic carbon atoms provided by the R* groups for each acid molecule represented by Formula (D-III). Examples of aromatic nuclei represented by the variable Ar* are the polyvalent aromatic radicals derived from benzene, naphthalene, anthracene, phenanthrene, indene, fluorene, biphenyl, and the like. Generally, the group represented by Ar* will be a polyvalent nucleus derived from benzene or naphthalene such as phenylenes and naphthylene, e.g., methylphenylenes, ethoxyphenylenes, nitrophenylenes, isopropylphenylenes, hydroxyphenylenes, mercaptophenylenes, N,N-diethylaminophenylenes, chlorophenylenes, dipropoxynaphthylenes, triethylnaphthylenes, and similar tri-, tetra-, pentavalent nuclei thereof, etc.
The R* groups in Formula (D-III) are usually purely hydrocarbyl groups, including groups such as alkyl or alkenyl radicals. However, the R* groups may contain small number substituents such as phenyl, cycloalkyl (e.g., cyclohexyl, cyclopentyl, etc.) and nonhydrocarbon groups such as nitro, amino, halo (e.g., chloro, bromo, etc.), lower alkoxy, lower alkyl mercapto, oxo substituents (i.e., xe2x95x90O), thio groups (i.e., xe2x95x90S), interrupting groups such as xe2x80x94NH, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, and the like provided the essentially hydrocarbon character of the R* group is retained. The hydrocarbon character is retained for purposes of this invention so long as any non-carbon atoms present in the R* groups do not account for more than about 10% of the total weight of the R* groups.
Examples of R* groups include butyl, isobutyl, pentyl, octyl, nonyl, dodecyl, docosyl, tetracontyl, 5-chlorohexyl, 4-ethoxypentyl, 2-hexenyl, e-cyclohexyloctyl, 4-(p-chlorophenyl)-octyl, 2,3,5-trimethylheptyl, 2-ethyl-5-methyloctyl, and substituents derived from polymerized olefins such as polychloroprenes, polyethylenes, polypropylenes, polyisobutylenes, ethylene-propylene copolymers, chlorinated olefin polymers, oxidized ethylene-propylene copolymers, and the like. Likewise, the group Ar may contain non-hydrocarbon substituents, for example, such diverse substituents as lower alkoxy, lower alkyl mercapto, nitro, halo, alkyl or alkenyl groups of less than 4 carbon atoms, hydroxy, mercapto, and the like.
A group of useful carboxylic acids are those of the formula: 
wherein in Formula (D-IV), R*, X1Ar*1m and a are as defined in Formula (D-III) and p is an integer of 1 to 4, usually 1 or 2. Within this group, a useful class of oil-soluble carboxylic acids are those of the formula: 
wherein in Formula (D-V), R** is an aliphatic hydrocarbon group containing at least 4 to about 400 carbon atoms, a is an integer of from 1 to 3, b is 1 or 2, c is zero, 1, or 2 and in one embodiment 1 with the proviso that R** and a are such that the acid molecules contain at least an average of about 12 aliphatic carbon atoms in the aliphatic hydrocarbon substituents per acid molecule. And within this latter group of oil-soluble carboxylic acids, the aliphatic-hydrocarbon substituted salicylic acids wherein each aliphatic hydrocarbon substituent contains an average of at least about 8 carbon atoms, and in one embodiment at least about 16 carbon atoms per substituent and one to three substituents per molecule are particularly useful. A useful aliphatic-hydrocarbon substituted salicylic acid is C16-C18 alkyl salicylic acid. Salts prepared from aliphatic-hydrocarbon substituted salicylic acids wherein the aliphatic hydrocarbon substituents are derived from polymerized olefins, particularly polymerized lower 1-mono-olefins such as polyethylene, polypropylene, polyisobutylene, ethylene/propylene copolymers and the like and having average carbon contents of about 30 to about 400 carbon atoms may be used.
Carboxylic acids of the type illustrated by the above formulae and processes for preparing their neutral and basic metal salts are well known and disclosed, for example, in such U.S. Pat. Nos. as 2,197,832; 2,197,835; 2,252,662; 2,252,664; 2,714,092; 3,410,798 and 3,595,791, which are incorporated herein by reference.
Another type of neutral and basic carboxylate salt used in this invention are those derived from hydrocarbon substituted succinic acids of the general formula 
wherein in Formula (D-VI), R* is as defined above in Formula (D-III). Such salts are set forth in U.S. Pat. Nos. 3,271,130; 3,567,637 and 3,632,610, which are hereby incorporated by reference in this regard.
Patents describing techniques for making basic salts of sulfonic acids and/or carboxylic acids include U.S. Pat. Nos. 2,501,731; 2,616,904; 2,616,905; 2,616,906; 2,616,911; 2,616,924; 2,616,925; 2,617,049, 2,777,874; 3,027,325; 3,256,186; 3,282,835; 3,384,585; 3,373,108; 3,368,396; 3,342,733; 3,320,162; 3,312,618; 3,318,809; 3,471,403; 3,488,284; 3,595,790; and 3,629,109. The disclosures of these patents are hereby incorporated by reference in the present specification.
A group of carboxylic acid derivatives that are useful are the lactones represented by the formula 
wherein in Formula (D-VII), R1, R2, R3, R4, R5 and R6 are independently H, hydrocarbyl groups or hydroxy substituted hydrocarbyl groups of from 1 to about 30 carbon atoms, with the proviso that the total number of carbon atoms must be sufficient to render the lactones oil soluble; R2 and R3 can be linked together to form an aliphatic or aromatic ring; and a is a number in the range of zero to about 4. Within this group the lactones represented by the following formula are useful 
wherein in Formula (D-VIII), R7 and R8 are aliphatic hydrocarbyl groups of from 1 to about 30 carbon atoms, a and b are numbers in the range of zero to 5 with the proviso that the sum of a and b does not exceed 5, and c is a number in the range of zero to 4. The procedures for preparing lactones of this type through intramolecular cyclization of hydroxy-containing carboxylic acids accompanied by the elimination of water are well known in the art. Generally, the cyclization is promoted by the presence of materials such as acetic anhydride, and the reaction is effected by heating the mixtures to elevated temperatures such as the reflux temperature while removing volatile materials including water. A useful lactone can be prepared by reacting an alkyl (e.g., dodecyl) phenol with glyoxylic acid at a molar ratio of 2:1.
Neutral and basic salts of phenols (generally known as phenates) are also useful in the compositions of this invention and well known to those skilled in the art. The phenols from which these phenates are formed are of the general formula
(R*)axe2x80x94(Ar*)xe2x80x94(OH)mxe2x80x83xe2x80x83(D-IX)
wherein in Formula (D-IX), R*, a, Ar*, and m have the same meaning and preferences as described hereinabove with reference to Formula (D-III). The same examples described with respect to Formula (D-III) also apply.
A commonly available class of phenates are those made from phenols of the general formula 
wherein in Formula (D-X), a is an integer of 1-3, b is of 1 or 2, z is 0 or 1, R1 is a substantially saturated hydrocarbon-based substituent having an average of from about 30 to about 400 aliphatic carbon atoms and R4 is selected from the group consisting of lower alkyl, lower alkoxyl, nitro, and halo groups.
A class of phenates for use in this invention are the basic (i.e., overbased, etc.) alkali and alkaline earth metal sulfurized phenates made by sulfurizing a phenol as described hereinabove with a sulfurizing agent such as sulfur, a sulfur halide, or sulfide or hydrosulfide salt. Techniques for making these sulfurized phenates are described in U.S. Pat. Nos. 2,680,096; 3,036,971 and 3,775,321 which are hereby incorporated by reference for their disclosures in this regard.
Other phenates that are useful are those that are made from phenols that have been linked through alkaline (e.g., methylene) bridges. These are made by reacting single or multi-ring phenols with aldehydes or ketones, typically, in the presence of an acid or basic catalyst. Such linked phenates as well as sulfurized phenates are described in detail in U.S. Pat. No. 3,350,038; particularly columns 6-8 thereof, which is hereby incorporated by reference for its disclosures in this regard.
Mixtures of two or more neutral and basic salts of the hereinabove described organic sulfur acids, carboxylic acids and phenols can be used in the compositions of this invention.
The alkali and alkaline earth metals that are useful include sodium, potassium, lithium, calcium, magnesium, strontium and barium, with calcium and magnesium being especially useful.
The metal salt (D) may be employed in the inventive lubricating oil composition at a concentration in the range of up to about 5% by weight, and in one embodiment about 0.5% to about 5% percent by weight, and in one embodiment about 1% to about 2.5% by weight. These compounds can be added directly to the lubricating oil composition. In one embodiment, however, they are diluted with a substantially inert, normally liquid organic diluent such as mineral oil, synthetic oil (e.g., ester of dicarboxylic acid), naptha, alkylated (e.g., C10-C13 alkyl)benzene, toluene or xylene to form an additive concentrate. These concentrates usually contain from about 1% to about 99% by weight, and in one embodiment about 10% to about 90% by weight of the diluent.
(E) Alkali or Alkaline Earth Metal Salt of a Hydrocarbon-Substituted Saligenin
The alkali or alkaline earth metal salt of a hydrocarbon-substituted saligenin may be a compound represented by the formula 
wherein in Formula (E-I): each X independently is xe2x80x94CHO or xe2x80x94CH2OH; each Y independently is xe2x80x94CH2xe2x80x94 or xe2x80x94CH2OCH2xe2x80x94; wherein the xe2x80x94CHO groups comprise at least about 10 mole percent of the X and Y groups; each M is independently a valence of an alkali or alkaline earth metal ion; each R is independently a hydrocarbyl group containing 1 to about 60 carbon atoms; m is 0 to about 10; n is 0 or 1 provided that when n is 0 the M is replaced with H; and each p is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R substituent and that the total number of carbon atoms in all R groups is at least 7; and further provided that if m is 1 or greater, then one of the X groups can be xe2x80x94H.
The alkali and alkaline earth metals that are useful include sodium, potassium, lithium, calcium, magnesium, strontium and barium, with calcium and magnesium being especially useful. In Formula (E-I), when the metal M is a divalent metal (e.g., calcium or magnesium) the other valence of M, not shown, may be satisfied by other anions or by association with an additional xe2x80x94Oxe2x88x92 functionality of the same saligenin derivative.
In Formula (E-I), each n is independently 0 or 1, provided that when n is 0, the M is replaced by H, that is, to form an unneutralized phenolic xe2x80x94OH group. The average value of n is typically about 0.1 to about 1.0. That is, the structure represents a partially or completely neutralized metal salt, a value of 1.0 corresponding to complete neutralization of each site by the metal ion M. The compound contains one aromatic ring or a multiplicity of aromatic rings linked by xe2x80x9cYxe2x80x9d groups, and also xe2x80x9cXxe2x80x9d groups. Since xe2x80x9cmxe2x80x9d can be 0 to about 10, this means that the number of such rings will typically be 1 to about 11, although it is to be understood that the upper limit of xe2x80x9cmxe2x80x9d is not a critical variable. In one embodiment, m is about 2 to about 9, and in one embodiment about 3 to about 8, and in one embodiment about 4 to about 6. If m is 1 or greater, then one of the X groups can be xe2x80x94H.
Most of the aromatic rings in Formula (E-I) contain at least one R substituent, which is a hydrocarbyl group, and in one embodiment an alkyl group, containing 1 to about 60 carbon atoms, and in one embodiment about 7 to about 28 carbon atoms, and in one embodiment about 9 to about 18 carbon atoms. R may comprise a mixture of various chain lengths, so that the foregoing numbers represent an average number of carbon atoms in the R groups (number average). R can be linear or branched. Each aromatic ring in the structure may be substituted with 0, 1, 2, or 3 such R groups (that is, p is 0, 1, 2, or 3), most typically 1. Different rings in a given molecule may contain different numbers of such substituents. At least one aromatic ring in the molecule must contain at least one R group, and the total number of carbon atoms in all the R groups in the molecule should be at least about 7, and in one embodiment at least about 12.
In Formula (E-I), the X and Y groups may be seen as groups derived from formaldehyde or a formaldehyde source, by condensative reaction with the aromatic molecule. While various species of X and Y may be present, the commonest species comprising X are xe2x80x94CHO (aldehyde functionality) and xe2x80x94CH2OH (hydroxymethyl functionality); similarly the commonest species comprising Y are xe2x80x94CH2xe2x80x94 (methylene bridge) and xe2x80x94CH2OCH2xe2x80x94 (ether bridge). The relative molar amounts of these species in a sample of the above material may be determined by 1H/13C NMR as each carbon and hydrogen nucleus has a distinctive environment and produces a distinctive signal. (The signal for the ether linkage, xe2x80x94CH2OCH2xe2x80x94 must be corrected for the presence of two carbon atoms, in order to arrive at a correct calculation of the molar amount of this material. Such a correction is well within the abilities of the person skilled in the art.)
In one embodiment, X is at least in part xe2x80x94CHO and such xe2x80x94CHO groups comprise at least about 10, and in one embodiment at least about 12, and in one embodiment at least about 15 mole percent of the X and Y groups. In one embodiment, the xe2x80x94CHO groups comprise about 20 to about 60 mole percent of the X and Y groups, and in one embodiment about 25 to about 40 mole percent of the X and Y groups.
In one embodiment, X is at least in part xe2x80x94CH2OH and such xe2x80x94CH2OH groups comprise about 10 to about 50 mole percent of the X and Y groups, and in one embodiment about 15 to about 30 mole percent of the X and Y groups.
In one embodiment in which m is non-zero, Y is at least in part xe2x80x94CH2xe2x80x94 and such xe2x80x94CH2xe2x80x94 groups comprise about 25 to about 55 mole percent of the X and Y groups, and in one embodiment about 32 to about 45 mole percent of the X and Y groups.
In one embodiment, Y is at least in part xe2x80x94CH2OCH2xe2x80x94 and such xe2x80x94CH2OCH2xe2x80x94 groups comprise about 5 to about 20 mole percent of the X and Y groups, and in one embodiment about 10 to about 16 mole percent of the X and Y groups.
The relative amounts of the various X and Y groups depends to a certain extent on the conditions of synthesis of the molecules. Under many conditions the amount of xe2x80x94CH2OCH2xe2x80x94 groups is relatively small compared to the other groups and is reasonably constant at about 13 to about 17 mole percent. Ignoring the amount of such ether groups and focusing on the relative amounts of the xe2x80x94CHO, xe2x80x94CH2OH, and xe2x80x94CH2xe2x80x94 groups, useful compositions have the following relative amounts of these three groups, the total of such amounts in each case being normalized to equal 100%:
The compound represented by Formula (E-I) may be a magnesium salt, and the presence of magnesium during the preparation of the compound is believed to be important in achieving the desired ratios of X and Y components described above. (After preparation of the compound, the Mg metal can be replaced by hydrogen, other metals, or ammonium if desired, by known methods.) The number of Mg ions in the composition is characterized by an average value of xe2x80x9cnxe2x80x9d of about 0.1 to about 1.0, and in one embodiment about 0.2 or about 0.4 to about 0.9, and in one embodiment about 0.6 to about 0.8, which correspond to about 20% to about 100%, and in one embodiment about 20% or about 40% to about 90%, and in one embodiment about 60% to about 80% neutralization by Mg. Since Mg is normally a divalent ion, it can neutralize up to two phenolic hydroxy groups. Those two hydroxy groups may be on the same or on different molecules. If the value of n is less than 1.0, this indicates that the hydroxy groups are less than completely neutralized by Mg ions. Alternatively, each Mg ion may be associated with one phenolic anion and an ion of another type such as a hydroxy (OHxe2x88x92) ion or carbonate ion (CO3xe2x88x92), while still providing an n value of 1.0. The specification that the average value of n is about 0.1 to about 1.0 is not directly applicable to basic or overbased versions of this material (described below) in which an excess of Mg or another cation can be present. It should be understood that, even in a basic material, some fraction of the phenolic OH groups may not have reacted with the magnesium and may retain the OH structure.
It is to be understood that in a sample of a large number of molecules, some individual molecules will exist which deviate from these parameters: for instance, there may be some molecules containing no R groups whatsoever. Likewise, some fraction of molecules may contain only one (or even zero) X groups, while some may contain more than two X groups. And some fraction of the aromatic groups may be linked by Y groups to more than two neighboring aromatic groups. These molecules could be considered as impurities, and their presence will not negate the present invention so long as the majority of the molecules of the composition are as described. In any event, compositions exhibiting this type of variability are to be construed as encompassed by the present invention and the description that a material is represented by the formula shown. There is a reasonable possibility that a significant fraction of the polynuclear molecules of the present invention may bear only a single X group. In order to explicitly account for this possibility, it is to be understood that if m is 1 or greater, one (but typically not both) of the X groups in the above structures can be xe2x80x94H.
The salts represented by Formula (E-I) can be prepared by combining a phenol substituted by the above-described R group with formaldehyde or a source of formaldehyde and magnesium oxide or magnesium hydroxide under reactive conditions, in the presence of a catalytic amount of a strong base.
Substituted phenols, and alkyl-substituted phenols in particular, are well known items of commerce. Alkylated phenols are described in greater detail in U.S. Pat. No. 2,777,874.
Formaldehyde and its equivalents are likewise well known. Common reactive equivalents of formaldehyde includes paraformaldehyde, trixoane, formalin and methal.
The relative molar amounts of the substituted phenol and the formaldehyde can be important in providing products with the desired structure and properties. In one embodiment, the substituted phenol and formaldehyde are reacted in equivalent ratios of about 1:1 to about 1:3 or about 1:4, and in one embodiment about 1:1.1 to about 1:2.9, and in one embodiment about 1:1.4 to about 1:2.6, and in one embodiment about 1:1.7 to about 1:2.3. Thus, in one embodiment, there is about a 2:1 equivalent ratio of formaldehyde to substituted phenol. (One equivalent of formaldehyde is considered to correspond to one H2CO unit; one equivalent of phenol is considered to be one mole of phenol.) In one embodiment of the Mg species, the mole ratio of alkylphenol:formaldehyde:Mg is about 1:1.4:0.4, that is, for example, about (1):(1.3 to 1.5):(0.3 to 0.5), the amounts being the quantities actually retained in the final product, rather than the amounts charged to the reaction.
The strong base may be sodium hydroxide or potassium hydroxide, and can be supplied in an aqueous solution.
The process can be conducted by combining the above components with an appropriate amount of magnesium oxide or magnesium hydroxide with heating and stirring. A diluent such as mineral oil or other diluent oil can be included to provide for suitable mobility of the components. An additional solvent such as an alcohol can be included if desired, although it is believed that the reaction may proceed more efficiently in the absence of additional solvent. The reaction can be conducted at room temperature or a slightly elevated temperature such as about 35 to about 120xc2x0 C., and in one embodiment about 70 to about 110xc2x0 C., and in one embodiment about 90 to about 100xc2x0 C. The temperature may be increased in stages. When water is present in the reaction mixture it is convenient to maintain the mixture at or below the normal boiling point of water. After reaction for a suitable time (e.g., about 30 minutes to about 5 hours, or about 1 to about 3 hours) the mixture can be heated to a higher temperature, preferably under reduced pressure, to strip off volatile materials. Favorable results may be obtained when the final temperature of this stripping step is about 100 to about 150xc2x0 C., and in one embodiment about 120 to about 145xc2x0 C.
Reaction under the conditions described above leads to a product which has a relatively high content of xe2x80x94CHO substituent groups, that is, about 10%, about 12%, about 15%, or greater.
The hydrocarbon-substituted saligenin salt (E) may be overbased. When these salts are overbased, the stoichiometrically excess metal can be magnesium or it can be another metal or a mixture of cations. The basically reacting metal compounds used to make these overbased salts are usually an alkali or alkaline earth metal compound (i.e., the Group IA, IIA, and IIB metals excluding francium and radium and typically excluding rubidium, cesium and beryllium), although other basically reacting metal compounds can be used. Compounds of Ca, Ba, Mg, Na and Li, such as their hydroxides and alkoxides of lower alkanols are usually used as basic metal compounds in preparing these overbased salts but others can be used as shown by the prior art referred to herein. Overbased salts containing a mixture of ions of two or more of these metals or other cations, including mixtures of alkaline earth metals such as Mg and Ca, can be used.
Overbased materials are generally prepared by reacting an acidic material (typically an inorganic acid, e.g., carbon dioxide, or lower carboxylic acid) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter. The acidic organic compound will, in the present instance, be the above-described saligenin derivative.
The acidic material used in preparing the overbased material can be a liquid such as formic acid, acetic acid, nitric acid, or sulfuric acid. Acetic acid is particularly useful. Gaseious acidic materials can also be used, such as HCl, SO2, SO3, CO2, or H2S, preferably CO2 or mixtures thereof, e.g., mixtures of CO2 and acetic acid. The acidic material, which may be an acidic gas, is reacted with the mixture under conditions to react, normally, with the majority of, or about 80-90% or about 85-90% of, the stoichiometric excess of the metal base. Strongly acidic materials, however, would normally be used in an amount less than an equivalent of the phenol, while weakly acidic materials such as CO2 can be used in excess.
A promoter is a chemical employed to facilitate the incorporation of metal into the basic metal compositions. The promoters are diverse and are well known in the art. A discussion of suitable promoters is found in U.S. Pat. Nos. 2,777,874, 2,695,910, and 2,616,904. These include the alcoholic and phenolic promoters. The alcoholic promoters include the alkanols of 1 to about 12 carbon atoms such as methanol, ethanol, amyl alcohol, octanol, isopropanol, and mixtures of these. Phenolic promoters include a variety of hydroxy-substituted benzenes and naphthalenes. A particularly useful class of phenols are the alkylated phenols of the type listed in U.S. Pat. No. 2,777,874, e.g., heptylphenols, octylphenols, and nonylphenols. Mixtures of various promoters are sometimes used.
Patents describing techniques for making basic salts of acidic organic compounds generally include U.S. Pat. Nos. 2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and 3,629,109.
The hydrocarbon-substituted saligenin salt (E) may be employed in the inventive lubricating oil composition at a concentration in the range of up to about 5% by weight, and in one embodiment about 0.5% to about 5% percent by weight, and in one embodiment about 1% to about 2.5% by weight. These compounds can be added directly to the lubricating oil composition. In one embodiment, however, they are diluted with a substantially inert, normally liquid organic diluent such as mineral oil, synthetic oil (e.g., ester of dicarboxylic acid), naptha, alkylated (e.g., C10-C13 alkyl)benzene, toluene or xylene to form an additive concentrate. These concentrates usually contain from about 1% to about 99% by weight, and in one embodiment about 10% to about 90% by weight of the diluent.
The following examples disclose the preparation of hydrocarbon-substituted saligenin salts that are useful in preparing the inventive lubricating oil composition. In the following examples as well as throughout the specification and claims, unless otherwise indicated, all parts and percentages are by weight and all temperatures are in degrees Celsius.